Probing drifting and nulling mechanisms through their interaction in PSR B0809+74 A. G. J. van Leeuwen, B. W. Stappers, R. Ramachandran and J. M. Rankin A&A, 399 1 (2003) 223-229 Published online: 05 February 2003 DOI: 10.1051/0004-6361:20021630